If your sink is blocked in Tivoli, you have several options to try. First its worth trying a few simple methods yourself; use a plunger or an old bottle with the bottom cut off and create suction over the stopper. Try pouring boiling water down the drains as this may help clear up any grease deposits that are blocking them (if compliant). If these steps don't work there probably some type of blockage further into drainpipe which would need more focused approaches such as using either chemical agents like vinegar solutions or getting professional assistance from Drainage Gloucestershire who may be able to snake out pet hair clogs etc. if required.